Hey everyone:

2011 F150 5.0 4x4- no mods. Issue: while driving, no matter what speed, every 9-10 seconds the truck will do what I describe as hiccup, slight jerk,. No codes. I have changed the coils as the mileage is at 240k, a new cat six months ago as a code popped. Mass air sensor good and clean. The “hitch” or hiccup is felt under feet. This started about 6 months ago. Yes, I still have the hard shift which is a real jolt. This current issue compared to that- the transmission jerk, is mild.I dont know where to start but am thinking plugs next?

thanks
Dave

 

Subscribing.

 

…after more reading a better description of the issue is the “motion” feels like a tap from the back bumper- hope this helps.

 

Is it possible that the torque converter on the transmission is slipping?

Does this occur with moderate acceleration or when driving on a moderate slope?

In either of the above, the conditions would result in a moderate load on the transmission allowing for early detection of a slipping transmission.

 

WHanson good call thinking convertor lockup

OP from what speed does it start? above 40? many develop lockup issues that feel like a misfire, bad u joint,out of balance driveshaft,tap in the rear, even a tire not being tight .

many times a bad lockup clutch fails to throw any faults

 

@carlie g… Just had the torque converter replaced/fixed on a GMC Acadia. I found it interesting that transmission slippage on that car caused the sensation in the drive train and suspension similar to small bumps in the pavement and also causing a resonance in the front suspension at 78 mph that was similar to unbalanced tires or mismatched shocks in the suspension. Really fools a person into thinking that the cause is related to suspension or steering.

in this case, the transmission slippage is being reported in the back end as that is what the drivetrain is powering.

I’m also wondering if this might cause the hard right lurch that was reported in some vehicles with 4WD enabled. The thought behind this is that the transient introduced to the drivetrain is felt in the imbalance or asymmetry of suspension components for higher frequency response.

 

yep all of the above can be from convertor clutch lockup issues ,really drives techs crazy with me being one of them. and right now i'm dealing with it in a 2023 nissan frontiers' 9 spd . under 40 it's super smooth above 40 omg feels like the driveshaft is coming out from under it, or a wheel is ready to fall off,

 

There's more than a few things that can cause this perceived *tap from behind* If you want to pinpoint the issue without spending your 401k or inheritance. Take it to a tech with the equipment to properly diagnose it.

 

Yes. The symptom; "lurch, tap from the rear bumper of miss feeling occurs at all speeds; If this is TCL "torque converter lockup" is a bad solenoid to blame? Or, does a mechanic have to first reproduce the symptoms then diagnose? What's the way into this fix?

Regards,
Dave

 

Yes, a tech would need to reproduce the failure to diagnose and would have the benefit of being able to examine the signals for shifting/switching solenoids of the transmission control to help in diagnosis.

In my prior “torque converter slippage” experience, the main behavior that clearly indicated to me that it was the transmission slippage was that it occurred with the moderate load such as holding steady speed while driving uphill on the highway. I had no gear shifting under that condition but could then feel the “bump” occurring. With steady velocity, the occurrence of the slippage rested in change in engine rpm of around 200-300 rpm.

I was returning north from Florida when this was occurring, so had the transmission fluid changed. Changing fluid reduced the amount of the steering vibration at 78 mph and also reduced the “bump” presence but the neither symptom went away,, just improved it by about 50%.

I would think that any irregular solenoid switching might be more reproducible during acceleration and deacceleration and less likely to occur at steady velocity whereas torque converter slippage would be present at steady velocity as I described driving up a moderate grade while intentionally avoiding transmission shift.

 

i'm with the others it's tek time, for a proper dia,
the op wrote 240k , there's going to a be a lot of wear inside the valve body which is where the issue starts

 

Thank you for the input. Yes, while holding steady throttle and ascending a hill or overpass, truck will bog down. Im wondering what Im getting into financially if it is torque converter issues?

 

My stepson just had his replaced on his 2017 5.0L truck under extended warranty at the dealer and the warranty bill was about $4K.

 

One needs a tech’diagnosis as the costs are highly variable based on what is found to be wrong.

A quick Google search says $600-$1000 to repair the torque converter for a F150, but I’m not sure that I believe that. Replacing the whole transmission is shown to cost as much as $5k-$7k.

My GM Acadia’s torque converter replacement cost $2k at the local transmission shop which I thought was fair.

 

costs depend on what we find worn out inside, with a full OH running 3 to s high as 5k , front wheel/awd drives are all in the upper range , as do performance add ons